Photographic emulsion containing alkyl quaternary salts of thiazoles and the like asantifoggants



Patented Sept. 27, 1938 UNITED STATES PATENT OFFICE PHOTOGBAPHIO EMULSION CONTAINING ALKYL QUATERNARY SALTS F THIA- ZOLES AND THE LIKE AS ANTIFOGGANTS Kodak Company, Jersey City, N. J.,

a corporation of New Jersey No Drawing. Application May 18, 1933, Serial No. 671,718. Renewed October 14, 1936.

Great Britain May 26, 1932 130laims.

This invention relates to anti-fogging agents for photographic emulsions, such as gelatino-silver-halide'emulsions, and more particularly to the use of alkyl quaternary salts of oxazoles, se-

6 lenasoles and thiazoles for that purpose.

Some sensitizing dyes, while being powerful color sensitizers, have a fogging action upon photographic emulsions containing them. It is also well known that when development of photo- 10 graphic film is continued for protracted periods, or at temperatures above normal, log is apt to result.

We have found that these harmful eflects can be decreased by adding a small proportion of one or more of the above heterocyclic compounds to l photographic emulsions.

An object of our invention, therefore, is to provide photographic emulsions of enhanced stability. Other objects will hereinafter appear.

We have discovered that alkyl quaternary salts 20 containing the nucleus Y i 25 where Y=O, 8 or Be may be used as stabilizing agents in the above sense.

Certain cyanine dyes containing the above nucleus exert a stabilizing or anti-fogging effect in addition to a specific color-sensitizing action.

30 For instance, when 1,1-diethylthiocarbocyanine iodide is used in conjunction with pinacyanol (1,1'-diethyl-2,2'-carbocyanine iodide), definite improvement in stability results. Such dyes, however, cannot be used if the color sensitiveness 35 which they confer is undesirable, but we have found that certain other compounds containing the above nucleus are eflectlve while at the same time not exerting a color-sensitizing action.

In general, the most eilective compounds are 40 salts containing the nucleus, specifically known as alkyl quaternary salts of the type.

R/ x where Y=O, S or Se 50 R=alkyl X=an acid radical A=a monovalent atom or grouping, such as hydrogen, alkyl, or aryl, and

D=vinylene, ethylene, phenylene, naphthylene,

etc.

Of these compounds, the most valuable are those in which Y=suliur or selenium. These salts, then are alkyl quaternary salts of thiazoline or selenazoline or of thiazole or selenazole bases. The

tendency to reduce fog is noticeable in some of the parent bases but, in general, the effect is much thiazoles (naphthoselenazoles) or the like. Any

of these rings may be substituted in positions where this is possible. For instance, the carbon atom situated between the two hetero atoms, and commonly known as the mu-carbon atom, may be linked to hydrogen, to alkyl, or to aryl. Examples of all these types will follow.

In anti-fogging effect, these quaternary salts vary greatly, as would be expected. The most useful of them are such as show a pronounced effect while causing relatively slight loss in sensitivity, although others desensitize somewhat more noticeably besides diminishing the fog. This desensitization, however, does not nullify their utility as anti-foggants. The eil'ect also varies with the type of emulsion used, so that one agent. is perhaps indicated for one emulsion, while another is better for a second emulsion.

In practice it has been found suitable to add only a very small amount of the anti-fogging agent to the emulsion just prior to coating. The amount varies, but on an average 2-8 mg. are added, in solution, to 100 cc. of a photographic emulsion containing sensitizers, if desired, such as is known to those skilled in the photographic art. Obviously more can be used where a badly fogging emulsion has to be corrected.

Examples The base 2-methylthiazoline shows a distinct tendency to reduce photographicfog. 2-methylthiazoline methiodide, however, shows this property to an enhanced degree. With 2,4-dimethylthiazole, the effect is not so pronounced but the ethiodide of the base shows the effect, although not particularly strongly. 2-methyl-4-phenylthiazole methiodide shows the effect but also causes excessive desensitization.

The base l-methylbenzothiazole only has a slight eifect, but its methiodide is very efiective. Similarly, l-methylbenzothiazole metho p-toluenesulfonate is quite powerful, and so are the etho-petoluenesulfonate, ethiodide and alliodide of 1 -methylbenzothiazole. The methiodide and ethiodide of benzothiazole itself are also very effective.

l-methyl-5-ethoxybenzothiazole ethiodide is moderately powerful in its action, and so is 1- ethylbenzothiazole ethiodide. l-phenylbenzothiazole metho-p-toluenesulfonate is also strong in its egfiect.

Salts of the naphthothiazoles are also very powerful. Among them may be noted Z-methylpenaphthothiazole meti'lo-p-toluenesulfonate, and also the methiodide and ethiodide of the same base. l-methyl-a-naphthothiazole' methiodide may also be used. I

1-phenyl-5-nitrobenzothiazole metho-p-toluene sulfonate is also powerful in its action, but it desensitizes strongly.

-Corresponding oxazole and selenazole compounds may likewise be employed, such, for in= stance, as l-methylbenzoselenazole metho ptoluene sulfonate, which is very'useful as an antifoggant.

The mercaptothiazoles are also useful for this purpose, examples being mercaptobenzthiazole, mercaptonaphthothiazole and the like, which are perfectly definite, easily available compounds.

In fact, the methods of preparation of all of the foregoing chemical compounds are described in the literature and/or in previously filed applications and resulting patents of L. G. S. Brooker, so that their preparation need not be described again here.

We are claiming as anti-foggants, therefore, those alkyl quaternary salts of the type- D/Y\OA in which Y=O, Be or S X=an acid radical A=a monovalent atom or grouping, such as hydrogen, alkyl or aryl, and

D=vinylene, ethylene, phenylene, naphthylene,

etc.

In the above formula where Y equals sulfur, for instance, the various substitutions for D would result as follows: 'vinylene would give a thiazole; ethylene, a thiazoline; phenylene, a benzothiazole; and naphthylene, a naphthothiazole alkyl quaternary salt. These are not to be confused with or even compared to the corresponding (thiazole) bases referred to in the prior art as being used for this purpose as many of them are ineffective as anti-foggants.

It will be obvious that while a small quantity of any one of the above compounds will usually give the desired anti-fogging effect, one may, if desirable, employ a mixture of a plurality of these agents. Furthermore, the anti-fogging agent may be added to the emulsion at any stage of its preparation which is convenient. It is usually added in methyl alcohol solution, although other types of solution will occur to those skilled in the art, depending upon the known solubility of the anti-fogging agent and the constitution of the emulsion to which it is added.

In addition, it has also been discovered that dyes of the thiocyanine type (such as 2,2'-dimethylthiocyanine chloride etc., see J. C. S. 1922, 121, 455; J. C. S. 1930, 2502) have an anti-fogging eflect upon photographic emulsions.

Photographic emulsions prepared as above are coated upon a suitable support to form a photographic element in a manner such as is well known to those skilled in this art.

Whatwe claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A gelatino-silver-halide emulsion containing, as an antlfogging agent, a compound having the general formula:

in which 2. A gelatino-silver-halide emulsion containing, as an antifogging agent, a compound having the general formula:

-Y n \C-A a x in which =an atom selected from the group consisting of oxygen, sulfur and selenium,

A=a member selected from the group consisting of hydrogen, alkyl groups and hydrocarbon groups of the benzene series,

D=a phenylene group,

. R=an alkyl group,

X=an acid radical.

3. A gelatino-silver-hallde emulsion containing, as an antifogging agent, a compound having the general formula:

Y D/ \CA R/ x in which X=an atom selected from the group consisting of oxygen, sulfur and selenium, A=a member selected from the group consisting of hydrogen, alkyl groups and hydrocarbon groups of the benzene series, D=a naphthylene group, R=an alkyl group, X=an acid radical.

4. A gelatino-silver-halide emulsion containing,

2,131,088 as an antifogging agent, a compound having the R=an alkyl group, X:an acid radical.

5. A gelatino-silver-halide emulsion containing,

as an antifogging agent, a compound having the general formula:

Y D \CA R x in which Y=an atom selected from the group consisting of oxygen, sulfur and selenium,

A=an alkyl group,

D=a phenylene group,

R=an alkyl group,

X an acid radical.

6. A gelatino-silver-halide emulsion containing, as an antifoggant, a compound of the general formula:

in which A=an alkyl group R=an alkyl group X=an acid radical.

'7. A gelatino-silver-halide emulsion containing, as an anti-fogging agent, a compound having the general formula C-CHr in which R=an alkyl group X=an acid radical.

8. A gelatino-silver-halide emulsion containing, as an antifoggant, a compound of the general formula ca R/ x in which A=an alkyl group R=an alkyl group x=an acid radical.

9. A gelatino-silver-halide emulsion containing, as an anti-fogging agent, a compound having the general formula in which R: alkyi X=an acid radical.

10. A gelatino-silver-haiide emulsion contain- :g a l-methyl-benzothiazole methiodide as an anti-fogging agent.

11. A gelatino-silver-halide emulsion containing a l-methyl-benzothiazole etho-p-toluenesulfonate as an anti-fogging agent.

12. A process for preventing fog in gelatinosilver-halide emulsions comprising adding to the finished emulsion a compound of the following general formula:

Y D/ \CA in which Y=an atom selected from the group consisting of oxygemsulfur and selenium,

A=a member selected from the group consisting of hydrogen, alkyl groups and hydrocarbon groups of the benzene series,

D=an organic group selected from the group consisting of vinylene, ethylene, phenylene and naphthylene groups,

R=an alkyl group,

X=an acid radical.

13. A photographic silver halide emulsion containing, as an antifogging agent, a compound having the general formula:

Y D/ \CA in which Y=an atom selected from the group consisting of oxygen, sulfur and selenium,

A=a member selected from the group consisting of hydrogen, alkyl groups and hydrocarbon groups of the benzene series,

=an organic group selected from the group consisting of vinylene, ethylene, phenylene and naphthylene groups,

R=an alkyl group,

x=an acid radical.

LESLIE a. s. BROOKER. mm .1, STAUD. 

